Devices, such as microelectromechanical system (MEMS) devices, have numerous applications, such as sensors, microphones and filters. MEMS devices include free-standing structures. For example, MEMS devices include free-standing structures with arbitrary clamping and geometries, such as cantilever structures. However, a major problem encountered with conventional MEMS devices is residual stress in the free-standing structures of the MEMS devices. Residual stress may result in bending, buckling or even failure in the release of the free-standing structure, depending on the stress. Furthermore, conventional processes for forming MEMS devices result in highly non-uniform stress distribution across the wafer map. The variation may be due to variations in process conditions across the wafer. The variation in stress affects the free-standing structures of the MEMS devices differently, depending on the stress at the location of the wafer. Such high non-uniformity in the stress distribution across the wafer undesirably contributes to a large variation in device performance, including failures. This negatively affects reliability and yields.
The present disclosure is directed to MEMS devices with localized strain and stress tuning to improve reliability and yields.